David Cameron will take his cabinet to Scotland tomorrow to highlight the importance to Scotland's oil industry of staying in the UK.

The prime minister insisted that it was the UK's "broad shoulders" which supported investment in the key industry, giving a "vital boost" to Scottish communities.

The importance of North Sea oil to Scotland's economy has made the future of the industry a politically sensitive issue in the independence debate.

Cameron's decision to hold a cabinet meeting in north-east Scotland is a sign of the oil industry's significance and a further indication of the Prime Minister's greater involvement in the debate over the country's future ahead of September's referendum.

It follows a major speech in which the prime minister delivered a heartfelt plea for Scotland to remain in the Union, pledging to "fight with all I have to keep us together".

Cameron said: "Two weeks ago I gave a speech setting out why I believe Scotland should remain part of the UK. In that speech I spoke about our long-term economic plan to move from a country sinking under too much debt to one that is dynamic, innovative and creating thousands of jobs for people right across our country.

"The plan is working. Last year the economy grew by the fastest annual rate since the financial crisis, we have the highest number of UK businesses on record and we have cut taxes for 25 million people.

"And last week we saw that 1.3 million more people are now in jobs across the whole UK compared with 2010 - that's 1.3 million more people with the security of a monthly pay packet and the peace of mind that brings.

"This week I will take the cabinet to Scotland where we will set out how the UK government can maximise the benefit of North Sea oil and gas to the UK economy for decades into the future, giving a vital boost to local communities and families across Scotland.

"For the past 300 years, Britain has led the way in finding new sources of energy. It is the strength of the UK's broad-based economy which can make the difference and ensure we can invest in our energy for the long-term future.

"I promise we will continue to use the UK's broad shoulders to invest in this vital industry so we can attract businesses, create jobs, develop new skills in our young people and ensure we can compete in the global race."

First Minister Alex Salmond, who is taking Scotland's cabinet to Portlethen tomorrow, has challenged Cameron to agree to a head-to-head debate while they are both in the north east.

Will Alex Salmond get the debate he wants with David Cameron?

Scottish Secretary Alistair Carmichael said: "The Government has a plan and it is working. But contrast this with those that have no plan - who respond to the very serious questions about issues such as currency and EU membership with bluster and diversion tactics rather than answers.

"A currency union is not going to happen and Alex Salmond knows it. He is the man without a plan. Independence is a hugely risky, dangerous and uncertain step and the time has come for him to start being honest with the people of Scotland about the consequences of leaving the UK family.

"Alex Salmond loves writing letters to the UK Government, but Scotland doesn't need a pen pal, we need answers. Scotland has the best of both worlds as part of the UK, we need to keep it that way."